我无法弄清楚的 Valgrind 错误

Question

This is the valgrind error that occurs when i run the program.

==137479== Conditional jump or move depends on uninitialised value(s)
==137479==    at 0x400B50: sdds::Ship::setShipEmpty() (Ship.cpp:25)
==137479==    by 0x400AF2: sdds::Ship::Ship() (Ship.cpp:20)
==137479==    by 0x401181: main (main_prof.cpp:49)
==137479==
==137479== Invalid write of size 1
==137479==    at 0x40097A: sdds::Engine::setEmpty() (Engine.cpp:19)
==137479==    by 0x400B3E: sdds::Ship::setShipEmpty() (Ship.cpp:26)
==137479==    by 0x400AF2: sdds::Ship::Ship() (Ship.cpp:20)
==137479==    by 0x401181: main (main_prof.cpp:49)
==137479==  Address 0x1fff001018 is not stack'd, malloc'd or (recently) free'd

My program at the moment is static and not using dynamic memory allocation, The goal is to create a function to set the variables to a safe empty state. When the object is valid set it accordingly. Here are my functions from Ship.cpp. Similarly, engine.cpp function to set to an empty state is pretty much the same.

    Ship::Ship()
    {
        setShipEmpty();
    }
    void Ship::setShipEmpty()
    {
        m_type[0] = '\0';
        for (int i = 0; i < m_engCnt; i++) {
            m_engines[i].setEmpty();
        m_engCnt = 0;
        }}
    
    Ship::Ship(const char* sType, const Engine* engines, int sizeOfEngine)
    {
        if (sType != nullptr && strlen(sType) > 0 && strlen(sType) < TYPE_MAX_SIZE && engines[0].get() > 0 && sizeOfEngine < 10) 
        {
            strcpy(m_type, sType);
            m_engCnt= sizeOfEngine ;

            for (int i = 0; i < sizeOfEngine; i++) {
                m_engines[i] = engines[i];
            }}
        else {
            setShipEmpty();
        }}

ship.h file

class Ship
    { ...private:
        Engine m_engines[10];
        char m_type[TYPE_MAX_SIZE+1];
        int m_engCnt;
      ....

engine.h file

const int TYPE_MAX_SIZE = 30;
    
    class Engine
    {
        double m_size;
        char m_type[TYPE_MAX_SIZE+1];
     public:...

engine.cpp

    void Engine::setEmpty()
    {
        m_type[0] = 0;
        m_size = 0;
    }

    Engine::Engine()
    {
        setEmpty();
    }

    Engine::Engine (const char* type, double size)
    {
        setEmpty();
        strcpy(m_type, type);
        m_size = size;
    }

Answer 1

Valgrind is complaining that you did not set a value for m_engCnt yet you are using it in a for loop. Given that m_engines is an Engine[10] , I suppose you want that loop to just go from 0 to 10.

Two points for improvement:

• Create a default constructor for Engine that does whatever setEmpty does now. That will allow you to skip the for loop in the Ship constructor.
• Even better, switch to a std::vector<Engine> so you don't have to manually initialize Engine s at the start that you will never use.